Hi, I have a few RGB LED reels(16ft/300 LEDs) that are powered using N-Channel MOSFET Transistors(IRL540) via arduino. This design only seems to work for short distances(5-7ft) before a color difference is noticeable due to the voltage drop. I measured the voltage at the side that was plugged in and the side that wasn't plugged into the power supply. The voltage at the input is ~12.3v, plenty of voltage. The voltage at the end of 16ft(5m) however, was 9.26v. How do I go about "injecting" voltage to the strip without adding another power supply or amplifier. My current power supply is a supernight 12v 30a power supply, which is capable of power up to 30ft or more of RGB LED strips. Again, the issue is the voltage drop. How do I fix this issue without adding an amplifier(short on time and money, so I really don't have much to work with) or additional power supply?
Would "injecting" another positive lead and some point in the strip be a solution and let the grounds go back through the entire thing?
The problem is the thin conductors on the strip. Because they are thin, their resistance is not low enough. With all that current flowing, there is a large voltage drop because V = I x I x R
Run 4 thicker conductor wires from one end of the strip to the other; R, G, B & GND. This will provide a second current path and lower the overall resistance, reducing the voltage drop.
Each 5m strip needs up to 18A, so your power supply can only safely run 1 strip. Your MOSFETs could probably run 3 strips but would likely need heatsinks, and, of course, a bigger PSU.
CrossRoads:
You could connect the supply to both ends and the middle. +12 & Gnd.
Ah, but these are RGB strips - you have to provide four power busses.
And note that you do indeed need to inject the power into the strip, so that at each injection point, current flows forward into the next part and back into the previous.
I did some experimenting and found that if I continue running the signal from the previous segment(red, green and blue) but add a different supply voltage(+) line from the psu or split from the existing one, the strip is then bright at the start of the new supply line. Knowing this, there has to be a simple way to run extra positive lines or split off of the main one to allow for power injection to make the strip work(once every 6ft?). I need to power 36ft of RGB LED strips off of this 12v 30a power supply unit. The other option is for me to get a dedicated power supply for each individual strip, which would be inefficient and a waste of money. There has to be a simple solution. Maybe a better strip that has thicker conductors?
I did what you suggested with dual feeding. I added a 2 way splitter on the 4 pin RGB connector and plugged each split into opposite sides of the reel (16ft) and there was plenty of juice and a VERY noticeable difference in the color of the LEDs. The only trouble with running extra cable to the other end of the LEDs is that I simply don't have enough cable to do so with AND the fact that these are 12ft segments and there will be 3 of them all running off of this power supply(12v 30a). The really nice thing is that the ones I am making for myself(there are 2 sets I am doing, one for an organization and another for me personally), is that they run off of ethernet jacks to run the power and signal, so what I did for my monitors is run 2 4 pin connectors off of one jack and then wire the plug coming off of the circuit board in a fashion that has 2 connections on all 8 pins. So 2 pins are voltage(+) and then 2 pins each for red, green, and blue. It works very well and that allows me to accomplish running a loop with the LEDs through my personal set on the back of each of my 3 24" computer monitors.